Thermal micropump with values formed from silicon plates

• US 5,375,979 A
• Filed: 06/16/1993
• Issued: 12/27/1994
• Est. Priority Date: 06/19/1992
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Trah, Hans-Peter
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): McAndrews, Jr., Roland G.
• Application Number:
  US08/078,132
• Time in Patent Office: 559 Days
• Field of Search: 417/52, 417/207
• US Class Current: 417/52
• CPC Class Codes: F04B 19/006 Micropumps F04B43/043 and F04B43/095 take precedence
• CPC Class Codes: F04B 19/24 Pumping by heat expansion of pumped fluid

Abstract

In a micropump having a working chamber (1), an intake valve (2), and a discharge valve (3), the valves (2,3) are etched out of silicon wafers (4,5). The gas in the working chamber (1) is heated by a heating element (6), so that an overpressure is produced in the working chamber. A partial vacuum is created by cooling the gas in the working chamber (1). The pump action of the micropump is achieved through the succession of overpressure and partial-vacuum cycles.

Claims

1. A micropump comprising:

a first plate constructed of silicon forming a first part of a chamber;

a second plate constructed of silicon forming a second part of the chamber and coupled to the first plate;

the chamber including an intake valve at a first location of the chamber for movement between a first position for allowing fluid to flow into the chamber and a second position for preventing fluid from flowing into the chamber;

the chamber further including a discharge valve at a second location of the chamber for movement between a third position for allowing fluid to flow out of the chamber and a fourth position for preventing fluid from flowing out of the chamber; and

a heating element member forming a third part of the chamber for controlling a temperature of fluid in the chamber, the heating element member including a carrier and a heating element;

wherein the intake and discharge valves are formed out of the first and second plates, and wherein the carrier is coupled to the first plate, with the carrier supporting the heating element at a first surface of the carrier and having a lower thermal capacity and a lower thermal conductivity at the first surface of the carrier than at a remainder of the carrier.

2. The micropump according to claim 1, wherein the intake valve moves between the first and second positions and the discharge valve moves between the third and fourth positions as a function of a pressure difference between a pressure of gas inside of the chamber and a pressure of gas outside of the chamber.

3. The micropump according to claim 1, wherein the intake valve and the discharge valve are etched out of the first and second plates.

4. The micropump according to claim 1, wherein the heating element includes an ohmic resistor.

5. The micropump according to claim 1, wherein the carrier has a lower thickness at the first surface than at the remainder of the carrier.

6. The micropump according to claim 1, wherein the carrier is constructed of a material having a thermal conductivity lower than a preselected value.

7. The micropump according to claim 1, wherein the micropump further comprises support means for stabilizing the carrier.

8. The micropump according to claim 2, wherein the support means is made from silicon, and is coupled to the first surface of the carrier.

9. The micropump according to claim 1, wherein the heating element member is heated by means electrical pulses.

10. The micropump according to claim 9, wherein the heating element member temperature controls a rate at which fluid is pumped.

11. The micropump according to claim 9, wherein a time interval between the electrical pulses controls a rate at which fluid is pumped.